Question

我的问题是：我使用Handler.postDelayed（）在500ms后运行动画。稍后在代码中我使用Handler.removeCallbacksAndMessages（）导致有时我想要运行另一个动画。问题是有时第一个动画开始但没有完成，我认为这是同步问题。

有没有办法检查是否启动了给postDelayed（）的Runnable，在这种情况下取消removeCallbacksAndMessages（）？

如果启动runnable的run（），removeCallbacksAndMessages有效吗？

代码是这样的：

Handler hand = new Handler();
if (counter==2) {
    one = (ImageView) findViewById(img_id);
    two = im;
    hand.postDelayed(new Runnable() {
        public void run() {
    applyAnim(0, 90, one, false);
    applyAnim(0, 90, two, false);
    counter = 0;
        }
    }, 750);
} else (counter == 3) {
    im.setClickable(false);
    hand.removeCallbacksAndMessages(null);
    counter = 1;
    applyScndAnim(0, 90, one, false);
    applyScndAnim(0, 90, two, false);
}

Answer 1

每次发布某个任务或发送一些消息时，此对象都会添加到队列中。当您调用removeCallbacksAndMessages时，将清除此队列。但是，当您调用removeCallbacksAndMessages时，正在调度（已从队列中拉出）的任务或消息将不会被取消。如果要停止任务，请将其作为线程执行：

public class DrawableTask implements Runnable{
    private boolean cancel = false;
    private boolean isBeingDispatched = false;
    public void cancel(){
        if (this.isBeingDispatched())
            this.cancel = true;
    }
    public boolean isBeingDispatched(){ return isBeingDispatched;}
    public void run(){
        isBeingDispatched = true;
        while(!cancel){
            //refresh 
        }
        cancel = false;
        isBeingDispatched = false;
    }
}

编辑：

private boolean cancel = false;
private boolean isBeingDispatched = false;

public void cancel(){
    if (this.isBeingDispatched())
        this.cancel = true;
}
public boolean isBeingDispatched(){ return isBeingDispatched;}

public void setHandlers(){
    Handler handler = new Handler(){
        public void handleMessage(Message msg){
             YourClassName.this.cancel = false;
             YourClassName.this.isBeingDispatched = true;
             while(! YourClassName.this.cancel){

                  //refresh
             }
             YourClassName.this.cancel = false;
             YourClassName.this.isBeingDispatched = false;
        }
    };
}

因此，您可以将此取消选项添加到处理程序中。当消息到达时，处理程序将执行此代码，如果在执行期间调用cancel（）方法处理程序将停止他正在做的任何事情。

android postDelayed和removeCallbacksAndMessages同步

1 个答案: